class Solution {
public:
    int bitSum(int n)
    {
        int sum=0;
        while(n)
        {
            int ret=n%10;
            sum+=(ret*ret);
            n/=10;
        }
        return sum;
    }
    bool isHappy(int n) {
        int slow=n,fast=bitSum(n);
        while(slow!=fast)
        {
            slow=bitSum(slow);
            fast=bitSum(bitSum(fast));
        }
        return slow==1;
    }